1. Field of the Invention
This invention relates to a transistor circuit provided with a source voltage ripple removal circuit, and more particularly to a transistor circuit provided with source voltage ripple removal function adapted for high output monolithic power integrated circuit (IC).
2. Description of the Prior Art
For the removal of ac ripple voltage component superposed on a dc source voltage, such circuits as a CR filter circuit using a capacitor and a resistor or a constant voltage circuit using a constant voltage element, e.g. Zener diode, and a resistor have been used.
The CR filter type ripple voltage removal circuit, however, is accompanied with such problems as that in a monolithic semiconductor IC Structure an excess of external connecting pins for the voltage ripple filter are needed which make the product price of the monolithic semiconductor IC expensive.
On the other hand, the constant voltage circuit type source voltage ripple removing circuit capable of being assembled in a monolithic IC is also accompanied with such drawbacks as that since a constant voltage element such as a Zener diode is used, the ripple removal function is lost at the supply voltages below a constant voltage determined by the Zener voltage, and that the amplification function of the signal transmitting transistor circuit is lost when the signal transmitting transistor is biased in saturation region upon the rise of the source voltage and hence that the operable source voltage region is narrow.